As you probably know, blackberries are borne on second year canes, so it is certainly possible that that area had been mowed/cut between last growing season and this one, which would neatly explain what you observed. Unfortunately, the truth is rarely that neat, and it could really be any number of other things as well.

Good luck!

Yes, the most likely cause was the cutting down of the yard center canes, resulting in first-year plants with no flowers.

If these are thorny blackberries, at least the yard center plants should be dug out. In any case, do not allow the new growth to arch over and re-root on the ground.

If they don't bloom next year give them some steamed bone meal which you can get at the local hardware store which will encourage blooming.